Objectives: To study biological properties of human lymphoma, sarcoma, carcinoma and retinoblastoma cells in vitro and to attempt to isolate oncogenic viruses from these cells. Major findings: 1. ChaGo cell line: Studies of this cell line derived from a human lung cancer which produces human chorionic gonadotropin in vitro have continued. A clonal line derived by Dr. Kim in our laboratory has been found to produce very high levels of the alpha subunit of hCG. In collaboration with Dr. Rosen's associates in NIAMDD, we have studied differences between ectopic and non-ectopic secretion of hCG and its subunits by comparing our clone from ChaGo with clonal lines from trophoblastic tumors derived by Dr. Peter Kohler. 2. Studies of retinoblastoma cells have continued in collaboration with Dr. Albert and Dr. Char. Fourteen patients with retinoblastoma, 5 normal volunteers and 6 other patients were tested for cell-mediated immunity by the 125I-iododeoxyuridine cytotoxicity assay against our retinoblastoma cell line and as a control against a breast cancer cell line. Eleven of the 14 patients with retinoblastoma had significantly increased cytotoxicity against the retinoblastoma cell line. 3. Studies of the human papovavirus isolated from the brain tumor of the Wiscott-Aldrich patient have continued in collaboration with Dr. Takemoto. The isolate has been shown to be serologically similar to the BK virus, and serum from the patient showed development of a higher antiviral antibody at least 1 year before the development of the tumor. Proposed course: Attempts to characterize the human papovavirus isolated from the brain tumor and to establish its role in the etiology of the tumor will continue. Studies of the factors involved in ectopic gonadotropin secretion by lung cancers will continue. Studies of the possible viral etiology of human retinoblastoma will also continue.